I built a chicken tractor for my 4 small chicks in spring but now they have outgrown it. I needed an expansion that would be extremely cheap-- so here's my idea.....My quail cages are about 6ft from my property fence and my duck cage is in front of my quail cage but attached to the property fence. I think I will put my tractor between the quail cage and the property fence then build a fence from the quail to the duck pen. That would give them about a 10x14 run I'm guessing and it wouldn't cost a thing........Its not allot of room but its better than the 3x8 tractor.........